Answer: 

Tsunamis are large waves generated by sudden movements of the ocean floor that displace a large volume of water. These are usually associated with earthquakes. According to the Global Historical Tsunami Database, since 1900, over 80% of likely tsunamis were generated by earthquakes. 

However, Tsunamis can also be triggered by other phenomena like submarine landslides and volcanic eruptions, or even due to the impact of meteorites and asteroids.

Formation of Tsunami: 

A tsunami is a series of extremely long waves caused by a large and sudden displacement of the ocean, usually the result of an earthquake below or near the ocean floor. This force creates waves that radiate outward in all directions away from their source, sometimes crossing entire ocean basins.  

Unlike wind-driven waves, which only travel through the topmost layer of the ocean, tsunamis move through the entire water column, from the ocean floor to the ocean surface. 

Different kinds of events can produce a tsunami: 

1. Earthquake: Earthquakes are generated by movements along fault zones associated with plate boundaries, which can cause vertical movement of the seafloor and large areas of horizontal motion. Shallow focus earthquakes in subduction zones are responsible for the most destructive tsunamis, which are caused by the amount of vertical and horizontal motion of the seafloor, the area over which it occurs, and the efficiency with which energy is transferred from the earth's crust to the ocean water. 

1. Landslides: Resulting in rock falls, icefalls, or underwater (submarine) landslides or slumps can generate displacement of water to create a tsunami. More often than thought, submarine landslides are often caused by earthquakes, large and small, therefore strengthening the force of an earthquake induced tsunami. 

1. Volcanic eruption: Volcanic eruptions can generate powerful and destructive tsunamis, most commonly occurring around the "Ring of Fire" area in the Pacific Ocean. The most destructive tsunami on record was caused by the explosion and collapse of the volcano Krakatoa in Indonesia in 1883, killing over 36,000 people and destroying coastal towns and villages. 

Eastern coast of India is more vulnerable to tsunamis than the western coast: 

• Location: The eastern coast of India is more vulnerable to tsunamis due to its location near the edge of the Indian Ocean and its proximity to earthquake-prone areas such as the  Circum-Pacific Belt.
• Closer to Sunda and Java trench: The eastern coast of India is located closer to the Sunda and Java trenches, which are two of the most active seismic zones in the world. These are the sources of many of the earthquakes that can produce tsunamis.  
• Sumatra Subduction zone: The eastern coast of India is also located closer to the Sumatra subduction zone, which is the site of the 2004 Indian Ocean tsunami. Following the 2004 Sumatra–Andaman earthquake, a number of studies have pointed out that Sumatra–Andaman subduction zone is one of the world׳s most potential hazardous zones for triggering possible giant tsunami that can have a larger population exposure. 
• Presence of bays and inlets:  The coast is made up of a series of bays and inlets, which can cause the water to become more turbulent and cause a tsunami to travel faster and farther.  
• Open water: The eastern coast of India is more exposed to open water, making it more vulnerable to tsunamis than the western coast. The western coast of India is more sheltered, which can help protect it from the destructive forces of a tsunami. 

The eastern coast of India is more vulnerable to tsunamis than the western coast due to its proximity to the Indian Ocean and the Bay of Bengal and the presence of numerous islands and shallow waters. The western coast of India is protected by the Western Ghats, which helps shield it from the effects of tsunamis.